1. Field of the Invention
The present invention generally relates to a substrate processing apparatus and method for performing predetermined processing on a substrate by utilizing a chemical reaction in the inside of a reaction enclosure. Incidentally, for example, an enclosure of double structure is used as the reaction enclosure. Further, for instance, CVD (Chemical Vapor Deposition) processing is adopted as the predetermined processing. Furthermore, for example, a thermal CVD processing or a plasma CVD processing is employed as this CVD processing.
2. Description of the Related Art
Generally, a film deposition apparatus for forming a predetermined thin film on a surface of a wafer is needed for producing a semiconductor device.
Example of this film deposition apparatus is CVD apparatus for performing film deposition by utilizing a chemical reaction in a hermetically enclosed reaction space.
Further, an example of such a CVD apparatus is a batch type CVD apparatus for forming predetermined thin films on a plurality of wafers at a time.
Furthermore, an example of such a batch type CVD apparatus is a vertical CVD apparatus wherein the plurality of wafers, on each of which thin film should be formed, are placed by being arranged vertically so that the horizontal sections of the wafers overlap with one another.
In the case of this vertical CVD apparatus, for instance, a reaction furnace of double structure, which has an outer tube and an inner tube, is used as the reaction enclosure.
In the vertical CVD apparatus using a reaction furnace of double structure as the reaction enclosure, a carrying-in/carrying-out opening is usually provided in the bottom end portion of the reaction furnace. Further, in this CVD apparatus, reaction gas for film deposition is usually supplied from the bottom end portion of the reaction furnace. Moreover, atmosphere contained in the inside of the reaction furnace is evacuated from the top end portion thereof through a space provided between the outer tube and the inner tube.
FIG. 13 is a side sectional diagram showing the configuration of the conventional vertical CVD apparatus which has the aforementioned reaction furnace of double structure. Hereinafter, the configuration of this conventional vertical CVD apparatus will be described. Incidentally, in the following description, this vertical CVD apparatus will be described as a low pressure CVD apparatus.
Vertical CVD apparatus 100 shown in this figure has: a reaction system 110 for forming a predetermined thin film on a wafer W by utilizing a chemical reaction in the inside (reaction space) of a reaction chamber 1a; a carrier system 120 for carrying the wafer W into the reaction chamber 1a and for carrying the wafer W therefrom; a gas supply system 130 of supplying into the reaction chamber a reaction gas for a film deposition process, an inert gas for performing what is called an after-purging process, and an inert gas for performing what is called an atmosphere restoring process; and an exhaust system 140 for the vacuum exhaust process (namely, the vacuum pumping process) of the reaction chamber 1a. 
Incidentally, the after-purging process is defined herein as a process consisting of the steps of supplying an inert gas into the reaction chamber 1a, and performing the vacuum-pumping of the reaction chamber 1a upon completion of the film deposition process, thereby purging the atmosphere away from the reaction chamber 1a by using the inert gas. Moreover, atmosphere restoring process is defined herein as a process consisting of the steps of stopping the vacuum exhaust process upon completion of the after-purging process, and then supplying an inert gas to the reaction chamber 1a, thereby restoring the inner pressure of the reaction chamber 1a to atmospheric pressure. This atmosphere restoring process is a process for preparing the apparatus for discharging the wafer W from the inside of the reaction chamber 1a. 
The reaction system 110 has a reaction furnace 111 for forming the reaction chamber 1a. This reaction furnace 111 is configured as a reaction furnace of double structure that has an outer tube 1M and an inner tube 2M. Throat 2a, through which a wafer W is carried in or out, is provided in the bottom end portion of this reaction furnace 111.
Gas supply system 130 has a gas supply nozzle 131 that is used to supply a reaction gas for the film deposition process, an inert gas for the after-purging process, and another inert gas for the ambient gas restoring process. Gas blowoff opening 4a of this gas supply nozzle 131 is provided in the neighborhood of the throat 2a of the furnace 111.
Exhaust system 140 has a main exhaust line 141 for performing a primary exhaust operation, an over-pressurization preventing line 142 for performing an over-pressurization preventing operation, and a bypass line 143 for performing a slow exhaust operation.
Incidentally, the primary exhaust operation is herein defined as an operation of performing a vacuum exhaust process on the reaction chamber 1a at high speed by increasing the exhaust conductance thereof. Further, the over-pressurization preventing operation is a vacuum exhaust process preventing the inner pressure of the reaction chamber 1a from exceeding atmospheric pressure in the atmosphere restoring process upon completion of the after-purging process. Moreover, the slow exhaust operation is herein defined as an operation of performing the vacuum exhaust process of the reaction chamber 1a at low speed by decreasing the exhaust conductance thereof.
Atmosphere exhaust port 5a of the exhaust system 140 is provided at a place where an atmosphere contained in the inside of the reaction chamber 1a is exhausted from the bottom end portion thereof through the space 3a between the outer tube 1M and the inner tube 2M.
In the case of the apparatus of the aforementioned configuration, when performing the film deposition process, first, a wafer W to be used therefor is carried into the reaction chamber 1a by the carrier system 120. Upon completion of this carrying- into operation, a slow exhaust operation is performed on the reaction chamber 1a by a bypass line 143. In this case, the atmosphere in the reaction chamber 1a is discharged from top end portion of the reaction furnace 111 through a space 3a between the outer tube 1M and the inner tube 2M.
When the degree of vacuum reaches a predetermined value as a result of a vacuum pumping process, a reaction gas for the film deposition is supplied by the gas supply system 130 to the vicinity of the throat 2a. Further, a primary exhaust operation is performed on the reaction chamber 1a by using a primary exhaust line 141. Thus, the reaction gas flows from the bottom portion (namely, a gas supply side) of the reaction furnace 111 to the top portion (namely, an exhaust side) and is dispersed into the reaction chamber 1a. As a consequence, predetermined thin film is formed on the surface of the wafer W. Moreover, an unreacted gas (namely, a part of the reaction gas, which does not react chemically) and the vapor of a reaction by-product are discharged from the top portion of the reaction furnace 111 through the space 3a. 
When predetermined thin film is deposited on the surface of the wafer W, an inert gas is supplied by the gas supply system 130 to the reaction chamber 1a. At that time, the primary exhaust operation having been performed by the line 141 is continued without interruption. Consequently, the atmosphere in the reaction chamber 1a is purged by the inert gas. Upon completion of this after-purging process, the primary exhaust operation is terminated. Thus, only the operation of supplying the inert gas is continued. Thereby, the internal pressure of the reaction chamber 1a is increased.
When the internal pressure of the reaction chamber 1a exceeds atmospheric pressure, a vacuum exhaust process is performed on the reaction chamber 1a by the over-pressurization preventing line 142. Thus, the internal pressure of the reaction chamber 1a is maintained at atmospheric pressure. Thereafter, the operations of supplying the inert gas and preventing the over-pressurization are terminated with predetermined timing. Then, the wafer W, on which thin film is deposited, is carried out of the reaction chamber 1a. 
In the herein-above description, there has described the configuration and operation of the conventional vertical CVD apparatus that has the reaction furnace 111 of the double structure.
However, in the case of the conventional vertical CVD apparatus 100 of the aforementioned configuration, during a time period when the inside of the reaction chamber 1a is opened to the outside through the throat 2a, outside air enters the inside of the reaction chamber 1a through this entrance 2a. Moreover, a gas-phase backward flow enters the reaction chamber 1a from an atmosphere exhaust path of the exhaust system 140. Thus, the vertical CVD apparatus as encountered the following four problems that
(1) First, during the time the inside of the reaction chamber 1a is opened to the outside through the throat 2a, the outside air enters the inside of the reaction chamber 1a. Thus, the inside of the reaction chamber 1a is contaminated.
(2) Second, during the time the inside of the reaction chamber 1a is opened to the outside through the throat 2a, the outside air enters the inside of the reaction chamber 1a. Thus, particles are generated in the reaction chamber 1a. 
Namely, even after the after-purging process is performed, a trace amount of unreacted gas is present in the reaction chamber 1a as a residue. When the outside air enters the inside of the reaction chamber 1a, this unreacted gas is mixed with water vapor contained in this outside air. This results in the generation of a contaminant. This contaminant acts as the particle. Therefore, when the outside air enters the inside of the reaction chamber 1a during the time the inside of the reaction chamber 1a is opened to the outside through the throat 2a, the particles are generated in the reaction chamber 1a. 
(3) Third, when performing the film deposition process, a haze (or mist) is generated on the surface of a wafer W in the case that the outside air enters the inside of the reaction chamber 1a during the time the inside of the reaction chamber 1a is opened to the outside through the entrance 2a. 
Namely, when the outside air enters the inside of the reaction chamber 1a during the time the inside of the reaction chamber 1a is opened to the outside through the throat 2a, vapor (outgassed), which is generated from a reaction by-product stuck onto the inner wall in the vicinity of the throat 2a, flows backward into the reaction chamber 1a. Thus, when forming film, a haze is produced due to this vapor on the surface of a wafer W.
(4) Fourth, in a time period during which the inside of the reaction chamber 1a is opened to the outside through the throat 2a, the inside of the reaction chamber 1a is contaminated by the gas-phase backward flow from the atmosphere exhaust path of the exhaust system 140 thereto.
Namely, when coming into contact with a low-temperature portion during discharge through the atmosphere exhaust path of the exhaust system 140, the unreacted gas or the vapor generated from the reaction by-product solidifies. This solidified gas is stuck onto the internal metallic surface of the atmosphere exhaust path or onto the quartz members therein as a reaction by-product. When the amount of this deposited by-product becomes large, this by-product may peel off the inner surface of the exhaust path and become particles.
Thus, in a time period during which the inside of the reaction chamber 1a is opened to the outside through the throat 2a, such particles flow from the atmosphere exhaust path of the exhaust system 140 into the inside of the reaction chamber 1a when the gas-phase backward flow enters the inside of the reaction chamber 1a from the atmosphere exhaust path of the exhaust system 140. As a result, the inside of the reaction chamber 1a is contaminated.
The present invention is accomplished to solve the aforementioned problems of the conventional apparatus and method.
Accordingly, an object of the present invention is to provide a substrate processing apparatus and method, by which an outside air and a gas-phase backward flow are restrained from entering the inside of a reaction chamber during the time the inside of a reaction chamber is opened to the outside through a substrate carrying-in/carrying-out opening.
To achieve the foregoing objects, in accordance with an aspect of the present invention, there is provided a substrate processing apparatus (hereunder sometimes referred to as a first substrate processing apparatus of the present invention) for performing a predetermined processing on a substrate by utilizing a chemical reaction in a reaction enclosure, which comprises: a reaction enclosure of double structure having: outer and inner tubular elements nearly coaxially provided therein; a first end portion in which a substrate carrying-in/carrying-out opening is provided and through which a reaction gas for processing a substrate is supplied; and a second end portion from which internal atmosphere is discharged through a space between the outer and inner tubular elements, and which further comprises: inert gas supply means for supplying an inert gas to the space between the outer and inner tubular elements in a predetermined term within a time period during which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening; and atmosphere exhaust means for exhausting an atmosphere contained in the reaction enclosure by using an atmosphere exhaust path for performing a substrate processing in the predetermined term within the time period during which the inside of the reaction enclosure is opened to the outside through the substrate carrying-in/carrying-out openings.
In the case of this first substrate processing apparatus of the present invention, during a predetermined term within a time period in which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening, an inert gas is supplied by the inner gas supply means to the space between the outer and inner tubular elements. Thus, the inner gas is supplied to the inside of the reaction enclosure from an exhaust port side from which an unreacted gas an so on is exhausted. In other words, the inert gas is supplied from the side opposite to the substrate carrying-in/carrying-out opening. As a result, the outside air is restrained from entering (or intruding into) the inside of the reaction chamber.
Moreover, during this term, the atmosphere contained in the reaction chamber is exhausted by the atmosphere exhaust means through the atmosphere exhaust path for processing a substrate. Thus, a gas-phase backward flow is restrained from entering the inside of the reaction enclosure from the atmosphere exhaust path for processing a substrate.
In the case of an embodiment (hereunder referred to as a second substrate processing apparatus of the present invention) of the first substrate processing apparatus, the predetermined term is a term during which a substrate is carried into and carried out of the reaction enclosure through the substrate carrying-in/carrying-out opening.
In the case of this second substrate processing apparatus of the present invention, the supplying of the inert gas into the reaction enclosure and the exhausting of the atmosphere contained in the reaction enclosure therefrom are performed during the term when the substrate to be processed is carried into the reaction enclosure and during the term when the processed substrate is carried out of the inside of the reaction enclosure. Thus, the consumption of the inert gas can be reduced in comparison with a configuration where the supplying of the inert gas and the exhausting of the atmosphere are always performed during the time period when the inside of the reaction enclosure is opened to the outside through the substrate carrying-in/carrying-out openings. Further, in the case of this second substrate processing apparatus, an ordinary O-ring can be employed in the atmosphere exhaust path, instead of an expensive high-heat-resistance O-ring. Thus, in the case that the O-ring is replaced with a new one when performing maintenance, the running cost can be decreased.
In the case of an embodiment (hereunder sometimes referred to as a third substrate processing apparatus of the present invention) of the first or second substrate processing apparatus of the present invention, the atmosphere exhaust means is adapted in such a manner as to exhaust the atmosphere contained in the reaction enclosure by performing a slow exhaust operation.
Thus, in the case of this third substrate processing apparatus of the present invention, the atmosphere in the reaction enclosure is exhausted by performing the slow exhaust operation. Thereby, a variation in internal pressure of the reaction enclosure due to the exhaust of the atmosphere in the reaction enclosure can be restrained. As a result, particles can be prevented from increasing owing to the following facts that this variation in the internal pressure causes film, which is deposited on the outer and inner tubular elements, to peel off and that such variation in the internal pressure causes the reaction by-products, which are deposited on the inner portion of the atmosphere exhaust path and on the inner wall in the vicinity of the substrate carrying-in/carrying-out opening, to come off and rise in the inner space of the reaction enclosure.
In the case of an embodiment (hereunder referred to as a fourth substrate processing apparatus of the present invention) of the first, second or third substrate processing apparatus of the present invention, a flow rate of an inert gas supplied from the inert gas supply means is set in such a manner as to be higher than a flow rate of an atmosphere exhausted by the atmosphere exhaust means.
In the case of this fourth substrate processing apparatus of the present invention, the flow rate of the inert gas is set in such a way as to be higher than the flow rate of the atmosphere. Thus, the internal pressure of the reaction enclosure is set as a positive pressure. Thereby, as compared with the case that the flow rate of the inert gas is equal to or less than the flow rate of the atmosphere, the advantageous effect of preventing the outside air from entering the reaction enclosure can be enhanced.
In the case of an embodiment (hereunder sometimes referred to as a fifth substrate apparatus of the present invention) of the first, second, third or fourth substrate processing apparatus of the present invention, a gas supply opening of the inert gas supply means is provided at a place where reaction by-products deposited on one or more inner walls of the reaction enclosure, which face the space between the outer and inner tubular elements and are in the vicinity of an atmosphere exhaust port for processing a substrate, are prevented from coming off and rising in the space.
In the case of this fifth substrate processing apparatus of the present invention, the gas supply opening of the inert gas supply means is provided at a place where reaction by-products deposited on the inner walls established in the vicinity of the atmosphere exhaust opening for processing a substrate are prevented from coming off and rising in the space. Thus, the generation of the particles due to the rise of the reaction by-product into the space can be restrained.
An embodiment (hereunder sometimes referred to as a sixth substrate processing apparatus of the present invention) of the first, second, third, fourth or fifth substrate processing apparatus of the present invention further comprises heating means for heating a substrate carried into the reaction enclosure. In this sixth substrate processing apparatus of the present invention, a gas supply opening of the inert gas supply means is provided at a place where the substrate is heated by this heating means.
In the case of this sixth substrate processing apparatus of the present invention, the gas supply opening of the gas supply means is provided at the position where the substrate is heated by the heating means. Thus, this gas supply opening can be provided at a place where no reaction by-product is deposited on the inner walls between the outer and inner tubular elements. Consequently, the generation of the particles due to the raising of the reaction by-product can be restrained.
In the case of an embodiment (hereunder sometimes referred to as a seventh substrate processing apparatus of the present invention) of the first, second, third, fourth, fifth or sixth substrate processing apparatus of the present invention, a plurality of gas supply openings of the inert gas supply means are provided.
In the case of this seventh substrate processing apparatus of the present invention, a plurality of gas supply openings are provided. Thus, the flow velocity of the inert gas can be restrained. Further, the plurality of gas supply openings may be suitably different from one another in respect of at least one of the position, orientation and size of the gas supply opening.
As is under stood from the foregoing description, an occurrence of convection of the inert gas in the space can be restrained. Thus, the raising of the reaction by-product into the space owing to the convection of the inert gas can be prevented. Consequently, an increase in particles due to the convection of the inert gas can be restrained.
Moreover, with such a configuration, the inert gas can be supplied to the entire space between the outer and inner tubular elements. Therefore, the inert gas can be fed to the entire inside of the reaction enclosure. Consequently, the outside air can be effectively prevented from entering the reaction enclosure through the substrate carrying-in/carrying-out opening.
In the case of an embodiment (hereunder sometimes referred to as an eighth substrate processing apparatus of the present invention) of the seventh substrate processing apparatus of the present invention, the plurality of gas supply openings are distributedly provided along a periphery of the inner tubular element. Further, a direction, in which the inert gas is supplied from each of the plurality of gas supply openings, is directed toward the second end portion of the reaction enclosure.
Thus, in the case of this eighth substrate processing apparatus of the present invention, the plurality of gas supply openings are distributedly provided along a periphery of the inner tubular element, and moreover, a direction, in which the inert gas is supplied from each of the plurality of gas supply openings, is directed toward the second end portion of the reaction enclosure. Consequently, the generation of convection of the inert gas can be restrained. Furthermore, the inert gas can be supplied to the entire space between the outer and inner tubular elements.
In the case of an embodiment (hereunder sometimes referred to as a ninth substrate processing apparatus of the present invention) of the first, second, third, fourth, fifth, sixth, seventh or eighth substrate processing apparatus of the present invention, the inert gas supply means is adapted to be able to control a flow rate of an inert gas to be supplied to an inside of the reaction enclosure, and the atmosphere exhaust means are adapted to be able to control a flow rate of an atmosphere to be exhausted from an inside of the reaction enclosure.
Thus, in the case of this ninth substrate processing apparatus of the present invention, the flow rate of the inert gas and the flow rate of the atmosphere can be controlled. Therefore, these flow rates can be set so that the intrusion of the outside air into the reaction enclosure and of the gas-phase backward flow can be prevented.
In the case of an embodiment (hereunder sometimes referred to as a tenth substrate processing apparatus of the present invention) of the ninth substrate processing apparatus of the present invention, the atmosphere exhaust means has: exhaust means for exhausting an atmosphere contained in the reaction enclosure; detection means for detecting a flow rate of an atmosphere to be exhausted by the exhaust means; and control means for controlling the flow rate of the atmosphere exhausted by the exhaust means so that the flow rate detected by the detection means has a predetermined value.
Thus, in the case of this tenth substrate processing apparatus of the present invention, the flow rate of the atmosphere to be exhausted by the exhaust means is detected by the detection means. Further, the flow rate of the atmosphere to be exhausted by the exhaust means is controlled by the control means so that the flow rate detected by the detection means becomes a predetermined flow rate.
Thereby, the flow rate of the atmosphere to be exhausted by the exhaust means is automatically controlled. As a consequence, even if a factor, by which a change in this flow rate can be caused, occurs after the flow rate of the atmosphere to be exhausted by the exhaust means is preliminarily set at a predetermined value, such a change in the flow rate can be prevented.
To achieve the foregoing objects of the present invention, in accordance with another aspect of the present invention, there is provided a substrate processing method for performing a predetermined processing on a substrate by utilizing a chemical reaction in a reaction enclosure which is a reaction enclosure of double structure having: outer and inner tubular elements nearly coaxially provided therein; a first end portion in which a substrate carrying-in/carrying-out opening is provided and through which a reaction gas for processing a substrate is supplied; and a second end portion from which internal atmosphere is discharged through a space between the outer and inner tubular elements. This method comprises a step of supplying an inert gas to the space between the outer and inner tubular elements in a predetermined term within a time period during which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening; and a step of exhausting the atmosphere by using an atmosphere exhaust path for performing a substrate processing in the predetermined term within the time period during which the inside of the reaction enclosure is opened to the outside through the substrate carrying-in/carrying-out openings.
In the case of this substrate processing method of the present invention, during a predetermined term within a time period in which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening, an inert gas is supplied to the space between the outer and inner tubular elements. Moreover, during this term, the atmosphere contained in the reaction enclosure is exhausted through the atmosphere exhaust path for processing a substrate. Thus, the outside air is prevented from entering the inside of the reaction enclosure. Moreover, a gas-phase backward flow is restrained from entering the inside of the reaction enclosure from the atmosphere exhaust path for processing a substrate.
To attain the foregoing objects, in accordance with still another aspect of the present invention, there is provided a substrate processing apparatus (hereunder sometimes referred to as an eleventh substrate processing apparatus of the present invention) for performing a predetermined processing on a substrate by utilizing a chemical reaction in a reaction enclosure that has a first end portion in which a substrate carrying-in/carrying-out opening is provided. This apparatus comprises: heating means, placed around the reaction enclosure, for heating a substrate carried into the reaction enclosure through the substrate carrying-in/carrying-out opening; inert gas supply means for supplying an inert gas to an inside of the reaction enclosure from a part, which is placed at a second end portion of the reaction enclosure and is to be heated by the heating means, in a predetermined term within a time period during which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening; and atmosphere exhaust means for exhausting an atmosphere contained in the reaction enclosure by a vacuum pumping by carrying out a slow exhaust operation, and by using an atmosphere exhaust path for performing a substrate processing in the predetermined term within the time period during which the inside of the reaction enclosure is opened to the outside through the substrate carrying-in/carrying-out openings.
Thus, in the case of this eleventh substrate processing apparatus of the present invention, an inert gas is supplied by the inert gas supply means to the inside of the reaction enclosure from a part, which is placed at a second end portion of the reaction enclosure and is to be heated by the heating means, in the predetermined term within the time period during which an inside of the reaction enclosure is opened to an outside through a substrate carrying-in/carrying-out opening. Thereby, the inert gas is fed to the inside of the reaction enclosure from a side opposite to the substrate carrying-in/carrying-out side thereof. Consequently, the outside air is restrained from entering the inside of the reaction enclosure.
Further, in this term, the atmosphere contained in the reaction enclosure is discharged therefrom by the atmosphere exhaust means through the atmosphere exhaust path for the substrate processing. Thus, the gas-phase backward flow is prevented from flowing into the reaction enclosure from the atmosphere exhaust path.
Furthermore, in the case of this eleventh substrate processing apparatus of the present invention, when the atmosphere in the reaction enclosure is discharged by the atmosphere exhaust means, the discharge of the atmosphere is conducted by performing a slow exhaust operation. Thereby, a variation in internal pressure of the reaction enclosure due to the exhaust of the atmosphere in the reaction enclosure can be restrained. As a result, particles can be prevented from increasing owing to the following facts that this variation in the internal pressure causes film, which is deposited on the inner wall of the reaction enclosure, to peel off and that such variation in the internal pressure causes the reaction by-products, which are deposited on the inner wall of the atmosphere exhaust path and on the inner wall in the vicinity of the substrate carrying-in/carrying-out opening, to come off and rise in the inner space of the reaction enclosure.
In the case of this eleventh substrate processing apparatus of the present invention, when supplying the inert gas in the reaction enclosure, this inert gas is supplied by the inert gas supply means to the inside of the reaction enclosure from a place namely, a part, which is placed at the second end portion of the reaction enclosure and should be heated by the heating means. Thus, this gas supply opening can be provided at a place where no reaction by-product is deposited on the inside of the reaction enclosure. Consequently, the generation of the particles due to the raising of the reaction by-product can be restrained.
Incidentally, the eleventh substrate processing apparatus can be applied not only to a substrate processing apparatus provided with a reaction enclosure of double structure but to a substrate processing apparatus provided with a reaction enclosure of a single structure.